Add docker container with iptables

Used for dropping packets on a specific port.

Needs to be launched with the NET_ADMIN and NET_RAW capabilities to be
able to actually be able to interact with iptables, this is done in
docker-compose.

Change-Id: I5093d19fbc269f42fe3e314e9344866fa5b79999
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

coin/provisioning/common/shared/testserver/iptables/Dockerfile

@@ -0,0 +1,4 @@
+FROM ubuntu:16.04
+ARG packages="iptables avahi-daemon"
+RUN apt-get update && apt-get install -y $packages && dpkg -l $packages
+EXPOSE 1357